The current state of the art of preoperative breast tumor localization requires the placement of either a metallic hookwire or a trail of medical grade powdered carbon suspension proximate to the tumor via a localization needle. In the former method, x-ray mammography, ultrasound, or magnetic resonance imaging is used to visualize the lesion in question. The breast is then fixed by compression means, non-compressive immobilization means, or, in the case of ultrasound, manually. A needle is inserted into the breast so that its tip lies proximate to the breast lesion. If carbon localization is used, a trail of carbon is formed from the lesion to the skin surface as the carbon suspension is injected through the needle as the needle is withdrawn. If hookwire localization is used, a fine metallic wire is inserted through the needle. The wire typically is bent or curved at the tip so that it forms a small hook. If the bend is sharp, the hook springs apart as it is passed distal to the tip of the localization needle. In this manner, it becomes substantially fixed at the site of the needle tip. The needle is then withdrawn leaving the hookwire in place. The patient is taken to surgery where the surgeon follows at least part of the carbon trail or hookwire to find the lesion for excision.
Copious references pertaining to the use of hook-wires in the imaging literature are available. Literature references include Gallagher, W. J., et al., "Minimal Volume Excision of Nonpalpable Breast Lesions," American Journal of Radiology, 152:957, 1989; Czarnecki, D. J., et al., "Toluidine Blue Dye as a Breast Localization Marker," American Journal of Radiology, 153:261, 1989; Schoenberger, S. G., et al., "New Coaxial Needle for Pre-operative Localization of Breast Abnormalities," British Journal of Radiology, 64:669, 1989; Langlois, S. L. P., Carter, M. L., "Carbon Localization of Impalpable Mammographic Abnormalities," Australian Radiolocry, 35:237, 1991; Czarnecki, D. J., et al., "Comparison of the Anchoring Strengths of the Kopans and Hawkins II Needle-hookwire Systems," Radiology, 183:573, 1992; D'Orsi, C. J., et al., "Complication Involving a Braided Hookwire Device," Radiology, 187:580, 1993; Ghiatas, A. A., et al., "Modified Localization Wire for Breast Lesions," European Radiology 2:266, 1992; Homer, M. J., et al., "Prebiopsy Needle Localization: Methods, Problems and Expected Results," Radiological Clinics of North America, 30:139, 1992; Homer, M. J., "Localization of Non-palpable Breast Lesions with the Curved-end, Retractable Wire," American Journal of Radiology, 151:919, 1989; Urritia, E. J., et al., "Retractable-barb Needle for Breast Lesion Localization," Radiology, 169:845, 1988. References pertaining to transillumination of breast tissue are: Jariman, O., "Time-resolved Transillumination of the Breast," Acta Radiologica, 33:228, 1992; and, Monsees, B., et al., "Light Scan Evaluation of Non-palpable Breast Lesions," Radiology, 167:352, 1987. A reference pertaining to optical fiber diffuser tips is Malone, D. E., et al., "Sonographic Changes During Hepatic Interstitial Laser Photocoagulation: an investigation of Three Optical Fiber Tips," Investigative Radiology, 27:804-813, 1992. The disclosures of the above cited references are hereby incorporated into and liberally drawn from for this background section.
Often the location of the hookwire tip is not readily apparent, and the surgeon must use measurements of the hookwire length, and visual triangulation to help guide him/her. A tugging maneuver is sometimes utilized in order to find the tip since the breast tissue will then move in the locality of the hookwire tip. This maneuver may displace the hookwire tip however. While it is possible to locate the tip of the hookwire fluoroscopically, this method requires a dedicated fluoroscopy suite and radiation protective aprons for all operating room personnel. In addition, unless the fluoroscopic tube can be angled to yield mediolateral and anteroposterior projections, the precise depth of the hookwire cannot be readily ascertained. For these reasons, fluoroscopic guidance is not feasible.
Intraoperative transillumination of the breast with an external light source has been used in conjunction with carbon localization for delineation of the dark carbon trail against the reddish glow of surrounding transilluminated breast tissue.
Both the hookwire and carbon trail methods are cumbersome in actual use. The tip of a hookwire cannot be seen through breast tissue, and the surgeon may have to search for it, commonly necessitating longer operating time, and a larger incision. A carbon trail tends to blacken surrounding tissue if it is cut into by a surgeon. Because of this, it is not always possible to determine the exact end of the trail. Commonly, the carbon trail may become broken if a steady stream of carbon is not injected. A method of localization that is easier to see and requires smaller incisions would offer many advantages.